1. Field
The present invention relates to a packet relay method and device.
2. Description of the Related Art
In a system relaying packets, normally, a redundancy is provided by establishing a protection route in addition to a working (operating) route.
Also, a link aggregation function prescribed on the Ethernet (registered trademark) is a widely utilized technology for the purpose of a bandwidth enhancement and a link redundancy, where a wide area Ethernet service offered by a carrier often uses the link aggregation function for a redundant routing, upon which a so-called one-sided link aggregation is often arranged for aggregating e.g. two physical ports (lines) to a link to restrict a transmission route to a single physical port in the form of a virtual single physical port (because of a need to strictly perform QoS control).
Also, for the confirmation of a protection route normality, a ping packet such as an ARP (Address Resolution Protocol) packet or ICMP (Internet Control Message Protocol) packet is used.
Such a conventional example will now be described referring to FIGS. 8-14. It is to be noted that while a link aggregation is not indispensable for the normality confirmation of a protection route described hereafter, an example with a link aggregation arranged will be described
FIGS. 8-10 show operations for normality confirmation of a protection route by transmitting a ping packet in a packet communication system formed of a transmitting device 1, a relay device 2 and a receiving device 3.
Particularly, FIG. 8 shows a setup state of the system before transmitting a ping packet, in which the transmitting device 1 sets one-sided hashing or hash sorting in a signal processor 10 so that all main signals may pass through a working route (route B-1) (step T1).
A conventional arrangement of the signal processor 10 is shown in FIG. 11, in which the signal processor 10 is formed of a packet transmitting processor 11, a hash sorting processor 12, a link aggregation table manager 13 and a link aggregation table 14, the above setting being preliminarily made in the hash sorting (hashing) processor 12 and the packet transmitting processor 11.
Such a signal processor is provided in the relay device 2 as signal processors 10_A and 10_B having the same arrangement, each being provided for port and having the same setting as the above step T1 (step T2). Also, in the receiving device 3, signal processors 10_C and 10_D are provided for port, each having the same arrangement and the same setting as well as a common link aggregation assigned an IP address, so as to respond to a ping packet destined for the IP address (step T3).
This makes the transmitting device 1 connect to the relay device 2 with link aggregations LA1 and LA2 and the relay device 2 connect to the receiving device 3 with link aggregations LA3 and LA4.
After the setting has been made, when a MAC packet such as shown in FIG. 12 is inputted as “a main signal packet” MP (see (1) in FIG. 11) to the signal processor 10 of the transmitting device 1, the packet transmitting processor 11 in the signal processor 10 extracts from the main signal packet MP a source address SA=a and a destination address DA=b, and identifies from a port having inputted the main signal packet MP a trunk of a destination link aggregation (hereinafter occasionally referred to simply as link aggregation), corresponding to the port. This trunk LA=y (“y” is an identifying reference numeral corresponding to e.g. the link aggregation LA1 for the transmitting device 1) is transmitted to the hash sorting processor 12 as transmitting packet information (2).
The hash sorting processor 12 looks up the table 14 through the table manager 13 with the link aggregation information (3) from among the information (2) as a key, thereby acquiring “ports D and E” corresponding to the link aggregation LA=y. Having recognized the main signal packet from the transmitting information (2), the hash sorting processor 12 performs hashing or hash sorting with the source address SA and the destination address DA (or VLAN-TAG), and selects e.g. the port D as a destination port (4) to be transmitted to the packet transmitting processor 11, so that the packet transmitting processor 11 outputs (5) the main signal packet MP to the port D.
It is to be noted that while as a result of hash sorting based on a hashing operation the hash sorting processor 12 may select the port E, it is now assumed that the port D is selected based on the one-sided hashing function for the link aggregation, and that while the IP address is also looked up, it is conventionally consistent only at the receiving device 3 but otherwise inconsistent.
The port D is thus connected to a working route B-1, through which the main signal packet MP is transmitted to the signal processor 10_B of the relay device 2. Also in this signal processor 10_B, the same operation as the signal processor 10 in the transmitting device 1 will be executed. Therefore, the main signal packet MP will be sent to the signal processor 10_D in the receiving device 3 through a working route B-2.
Then, the signal processor 10_D, when its destination address is found to be consistent with the one assigned in the main signal packet MP, takes in the main signal packet MP, but otherwise passes through it.
Next, an operation at the time of transmitting “ping packet” will be described referring to FIG. 9, in which the same operation as the case shown in FIG. 8 is performed when the main signal packet MP is provided to the signal processor 10, where the ping packet is generated within the packet transmitting processor 11 of the transmitting device 1 and sent out.
Namely, the packet transmitting processor 11 of the signal processor 10 generates as a ping packet an ARP Ethernet packet shown in FIG. 13 and outputs (5) it from the protection port E preset.
Accordingly, the ARP packet is sent to the signal processor 10_A of the relay device 2 through the protection route A-1 from the port E (step T11).
The signal processor 10_A of the relay device 2 also has the same arrangement as FIG. 11, where the packet transmitting processor 11, similar to the case of FIG. 8, transmits as the transmitting packet information (2) the source address SA, the destination address DA and the trunk information “y” of the destination link aggregation LA corresponding to the port to the hash sorting processor 12.
Upon receipt of the transmitting packet information (2), the hash sorting processor 12 looks up the table 14 through the table manager 13, thereby finding from the LA read information (3) that what corresponds to the trunk LA=y of the destination link aggregation are the ports E and D.
Since the transmitting packet information (2) includes no ARP packet information similar to the case of the main signal packet, the hash sorting processor 12 performs hash sorting based on a hashing operation and outputs (5) a ping packet from the working port D (this may be the port E but assumes the port D according to the one-sided hashing function of the link aggregation as aforementioned), so that the ARP packet is transmitted to the working route B-2 (step T12).
The signal processor 10_B in the receiving device 3 having received such an ARP packet recognizes from a destination IP address within “ARP request/response” that the ARP packet is destined for the link aggregation of the processor 10_B itself, and then returns it to the route B-2 from the same port having inputted this ARP packet (step T13).
The ARP packet returned is subjected to the same signal processing as well as the hash sorting at the signal processor 10_B in the relay device 2, whereas even with the one-sided hash sorting in the example shown, at this time, the port E (protection side) happens to be selected and the packet is to be returned to the signal processor 10 of the transmitting device 1 through the protection route A_1 connected to the port E.
In the example of FIG. 9, as described above, the ping packet is returned via the same route, but is returned via a different route in the example shown in FIG. 10.
Namely, at the time of ping response shown in FIG. 10, when the signal processor 10_D of the receiving device 3 returns a ping response from the received port (step T21), and the ping response is inputted to the signal processor 10_B of the relay device 2 through the working route B-2. Since the signal processor 10_B treats even the ping packet as a main signal as described above, the ping packet is subjected to the hash sorting as with the main signal packet, so that the port D (working side) is selected according to the one-sided hash sorting and the ping packet is transmitted to the working route B-1 (step T22).
Therefore, the ARP packet having been returned through the working route B-1 is received by the signal processor 10 of the transmitting device 1 where the route confirmation is to be made (step T23).
It is to be noted that while the above description has mentioned a case where a link aggregation is arranged, a case where no link aggregation is arranged has the same operation.
Also, while an ARP packet is exemplified as a ping packet, an ICMP packet can also be mentioned as shown in FIG. 14, where an ICMP portion recognizes it as an ICMP packet and presets the IP address of the destination link aggregation, exhibiting a similar operation to the ARP packet.
As a reference example, there is a failure monitoring process system of the network for communication between node devices connected to duplexed LANs comprises a router for connecting the duplexed LAN to another LAN, and two operational/standby interfaces for communication between node devices through the duplicate LAN having a common network address with each having physical address. It also comprises a failure detector which judges that the LAN connected to one interface is normal and the LAN connected to one interface is in trouble if the response packet whose destination is the network address, and physical address of one interface is received from the router no response packet is received when a packet whose destination is router's network address and physical address is transmitted to the router from one of two interfaces (see e.g. Japanese Patent Application Publication No. 2005-244672).
As a further reference example, there is an ATM exchange apparatus wherein inside an intersecting selector connecting a former-stage function block and a latter function block of an ATM exchange, filters are provided, and ATM cells in which working or protection apparatus state information are set in an overhead area in working and protection apparatus, thereby only passing ATM cells where working apparatus state information is set by the filters (see e.g. Japanese Patent Application Publication No. 08-079268).
In the prior art example shown in FIGS. 8-10 above, when a ping packet for confirming a normality of a protection route as shown in FIG. 9 is transmitted from the transmitting device 1 and then responsively returns from the receiving device 3 through the relay device 2, the ping packet traces the identical route. However, while between the transmitting device 1 and the relay device 2 the ping packet passes through the protection route, between the relay device 2 and the receiving device 3 it does not pass through the protection route A-2, failing to confirm the normality of the protection route.
Also, in the case shown in FIG. 10, the return route of the ping packet is the same as the main signal packet, whereas since between the devices link aggregations are formed, even though the ping packet is received at a port (working side port D) different from a destination port (protection side port E), one falsely confirms or recognizes due to the one-sided hash sorting that the ping packet has been normally received (step T23), so that it is also disadvantageous in that a normality of the protection route A-2 can not be confirmed.